What do you mean exactly by "blocked"?
I know that if your number or somebody else's number is on the Do Not Call list, it will be listed as Restricted on the phone display during a call. If I get a missed call and it's listed as Restricted and nothing else, it makes me crazy because I have to figure out who called me. Fortunately, it's usually either my sister or my mother, but it can be somebody else, too. Is that what you mean?